U.S. patent application number 11/690330 was filed with the patent office on 2007-10-04 for packet switched radio telecommunication system supporting hard handover and method for hard handover.
This patent application is currently assigned to PANTECH & CURITEL COMMUNICATIONS, INC.. Invention is credited to Kil Soo Kim, Sung Jin Suh.
Application Number | 20070230402 11/690330 |
Document ID | / |
Family ID | 38330216 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070230402 |
Kind Code |
A1 |
Kim; Kil Soo ; et
al. |
October 4, 2007 |
PACKET SWITCHED RADIO TELECOMMUNICATION SYSTEM SUPPORTING HARD
HANDOVER AND METHOD FOR HARD HANDOVER
Abstract
A packet switched radio telecommunication system supporting hard
handover adapts Always_on technology to a link between a target
packet data serving node (PDSN) and a support PDSN. The support
PDSN assigns a temporary IP address to a mobile terminal in its
service area, and transmits handover data and the mobile terminal's
temporary IP address to the target PDSN via a direct link when the
mobile terminal leaves the service area. The target PDSN, upon
receiving a registration request for the temporary IP address from
the mobile terminal moved to its service area, temporarily
registers the temporary IP address in an IP pool. The target PDSN
receives down-link frame data for the mobile terminal at the
temporarily registered IP address from the support PDSN via the
direct link. A new temporary IP address is assigned by the target
PDSN when data transmission/reception is complete to the mobile
terminal.
Inventors: |
Kim; Kil Soo; (Seoul,
KR) ; Suh; Sung Jin; (Seoul, KR) |
Correspondence
Address: |
H.C. PARK & ASSOCIATES, PLC
8500 LEESBURG PIKE, SUITE 7500
VIENNA
VA
22182
US
|
Assignee: |
PANTECH & CURITEL
COMMUNICATIONS, INC.
Seoul
KR
|
Family ID: |
38330216 |
Appl. No.: |
11/690330 |
Filed: |
March 23, 2007 |
Current U.S.
Class: |
370/331 |
Current CPC
Class: |
H04W 92/24 20130101;
H04W 80/04 20130101; H04W 88/005 20130101; H04W 36/0011
20130101 |
Class at
Publication: |
370/331 |
International
Class: |
H04Q 7/00 20060101
H04Q007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2006 |
KR |
10-2006-0028664 |
Claims
1. A packet switched radio telecommunication system, comprising: a
support packet data serving node (PDSN) to assign a temporary
Internet Protocol (IP) address to a mobile terminal in its service
area, to maintain a direct link to a neighboring PDSN, and to
transmit handover data and the temporary IP address to the
neighboring PDSN via the direct link; and a target PDSN to register
the temporary IP address in an IP pool in response to a request
from the mobile terminal moved into a service area of the target
PDSN, wherein the target PDSN receives down-link frame data from
the support PDSN via the direct link, the down-link frame data
being transmitted to the mobile terminal at the temporary IP
address, and wherein the neighboring PDSN is the target PDSN.
2. The packet switched radio telecommunication system of claim 1,
wherein the mobile terminal gives back the temporary IP address to
the support PDSN after moving to the service area of the target
PDSN, and is assigned with a new temporary IP address corresponding
to an IP address from the IP pool.
3. The packet switched radio telecommunication system of claim 2,
wherein the mobile terminal gives back the temporary IP address to
the support PDSN after data transmission or reception is
complete.
4. The packet switched radio telecommunication system of claim 2,
wherein the mobile terminal gives back the temporary IP address to
the support PDSN if the mobile terminal enters a dormant state.
5. A method for handing over a mobile terminal from a support
packet data serving node (PDSN) to a target PDSN, the method
comprising: assigning a temporary IP address to the mobile terminal
in a service area of the support PDSN; configuring a direct link
between the support PDSN and the target PDSN and maintaining a
protocol configuration; transmitting handover data and a temporary
IP address of the mobile terminal from the support PDSN to the
target PDSN via the direct link; requesting registration of the
temporary IP address from the target PDSN; and registering the
temporary IP address of the mobile terminal in an IP pool of the
target PDSN.
6. The method of claim 5, further comprising: transmitting
down-link frame data transmitted from a core network from the
support PDSN to the target PDSN via the direct link; and
transmitting the down-link frame data to the mobile terminal in a
service area of the target PDSN at the temporary IP address.
7. The method of claim 6, further comprising: giving back the
temporary IP address to the support PDSN; and assigning the mobile
terminal with a new temporary IP address through a Point to Point
Protocol (PPP) connection to the target PDSN, and registering the
new temporary IP address in the core network.
8. The method of claim 7, wherein the core network comprises a home
agent of the mobile terminal.
9. The method of claim 7, wherein the new temporary IP address
corresponds to an IP address from an IP pool in the target
PDSN.
10. The method of claim 7, wherein the mobile terminal gives back
the temporary IP address to the support PDSN after data
transmission or reception is complete at the mobile terminal.
11. The method of claim 7, wherein the mobile terminal gives back
the temporary IP address to the support PDSN if the mobile terminal
enters a dormant state.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority from and the benefit
of Korean Patent Application No. 10-2006-0028664, filed on Mar. 29,
2006, which is hereby incorporated by reference for all purposes as
if fully set forth herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a packet switched radio
telecommunication system supporting hard handover and a method for
hard handover, and more particularly to a packet switched radio
telecommunication system supporting mobile IP hard handover without
data corruption or data loss, and a method for hard handover.
[0004] 2. Background of the Invention
[0005] Mobile Internet Protocol (IP) is a standard IP that
incorporates mobility of devices connected to the internet. Under
Mobile IP, an IP address is allocated to a mobile terminal when a
mobile terminal roams and temporarily gains access to the internet
via a fixed network other than the mobile terminal's home
network.
[0006] FIG. 1 is a block diagram of a network of a conventional
packet switched radio telecommunication system. Mobile IP will now
be described in detail with reference to FIG. 1.
[0007] Upon initial subscription, a mobile terminal (MS) 101 is
connected to the Internet 106 via its home network area and
receives an inherent IP address from its home agent (HA) 108.
However, when the MS moves from its home network area to a foreign
network area, the MS 101 is assigned a care-of address (CoA)
corresponding to an IP address of the foreign agent (FA) 105 in the
foreign network area and is assigned a temporary IP address from
the FA 105. Then, a server 107 transmits data to the HA 108 using
the inherent IP address of the MS 101, even if the MS 101 has moved
outside of its home network. The HA 108 receives data intended for
the MS 101, encapsulates the data, and transmits the encapsulated
data to the CoA corresponding to the IP address of the FA 105 in
the foreign network area. The FA 105 then transmits data to the MS
101 using to the temporary IP address. Thus, data transmitted by
the server 107 to the MS 101 is routed through the HA 108 and the
FA 105 in the foreign network area.
[0008] In the conventional mobile IP structure described above,
when the MS 101 carries out handover, the MS 101 first transmits a
handover request to the HA 108 via a support base station
controller (BSC) 102, which may be combined with a packet control
function (PCF), and a support packet data serving node (PDSN) 103.
Further, when a target FA 105 in the foreign network area to which
the MS 101 is moving is connected to a target PDSN 105 and a target
BSC/PCF 104, the MS 101 disconnects a link set to the support BSC
102 and the support PDSN 103, sets a new link to the target PSDN/FA
105, and is assigned with a temporary IP address from the target FA
105. Thus, data transmitted from the server 107 is routed by the HA
108 to the MS 101 at the temporary IP address provided by the
target FA 105.
[0009] The above-mentioned prior handover method has a problem in
that when a MS 101 is hard handed over from a previous channel in
the home network area to a new channel in the foreign network area,
the connection to the home network area channel is broken before
the connection to the foreign network area channel occurs.
Accordingly, up-link and down-link paths are interrupted with
respect to radio interface, and frame loss may result.
[0010] Korean Patent Application Publication No. 10-2001-0062319
discloses a hard handover method in which a direct link is
established between the support PDSN 103 and the target PDSN 105,
thereby causing a shorter disconnection with the MS 101 during the
hard handover.
[0011] More specifically, a target PDSN 105 requests the support
PDSN 103 for a temporary direct link. Then, when an up-link frame
is transmitted from an MS 101 to a support PDSN 103 after the
target PDSN 105 requests a temporary direct link with the support
PDSN 103, the support PDSN 103 transmits the up-link frame from the
MS 101 to the target PDSN 105 via the temporary direct link. At the
same time, the support PDSN 103 transmits the up-link frame to a
core network including the Internet 106. Then, the core network
concurrently transmits down-link frames to both the target PDSN 105
and the support PDSN 103. The target PDSN 105 determines a handover
completion time and transmits a handover command signal to the
support PDSN 103 via the core network.
[0012] However, with Korean Patent Application Publication No.
10-2001-0062319, there may be delays associated with requesting and
setting a temporary direct link between the support PDSN 103 and
the target PDSN 105. Further, there may be delays associated with
requesting the core network for handover and receiving a
corresponding response. Because the request passes through the core
network including the Internet 106, the delay time may be much
greater. Furthermore, a network load is doubled since data is
transmitted from the core network to both the target PDSN 105 and
the support PDSN 103 until handover is complete.
SUMMARY OF THE INVENTION
[0013] The present invention provides a packet switched radio
telecommunication system supporting hard handover without data
transmission delay and data corruption or loss and a method for
hard handover.
[0014] Additional features of the invention will be set forth as
follows, and in part will be apparent from the description, or may
be learned by practice of the invention.
[0015] The present invention discloses a packet switched radio
telecommunication system including a support packet data serving
node (PDSN) to assign a temporary Internet Protocol (IP) address to
a mobile terminal in its service area, to maintain a direct link to
a neighboring PDSN, and to transmit handover data and the temporary
IP address to the neighboring PDSN via the direct link, and a
target PDSN to register the temporary IP address in an IP pool in
response to a request from the mobile terminal moved into a service
area of the target PDSN. Further, the target PDSN receives
down-link frame data from the support PDSN via the direct link, the
down-link frame data being transmitted to the mobile terminal at
the temporary IP address, and the neighboring PDSN is the target
PDSN.
[0016] The present invention also discloses a method for handing
over a mobile terminal from a support packet data serving node
(PDSN) to a target PDSN. The method includes assigning a temporary
IP address to the mobile terminal in a service area of the support
PDSN, configuring a direct link between the support PDSN and the
target PDSN and maintaining a protocol configuration, transmitting
handover data and a temporary IP address of the mobile terminal
from the support PDSN to the target PDSN via the direct link,
requesting registration of the temporary IP address from the target
PDSN, and registering the temporary IP address of the mobile
terminal in an IP pool of the target PDSN.
[0017] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention, and together with the description serve to explain
the principles of the invention.
[0019] FIG. 1 is a block diagram of a network of a conventional
packet switched radio telecommunication system.
[0020] FIG. 2 is a block diagram of a network of a packet switched
radio telecommunication system according to an exemplary embodiment
of the present invention.
[0021] FIG. 3 is a flow chart illustrating a method for hard
handover in the packet switched radio telecommunication system
according to an exemplary embodiment of the present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0022] The invention is described more fully hereinafter with
reference to the accompanying drawings, in which embodiments of the
invention are shown. This invention may, however, be embodied in
many different forms and should not be construed as limited to the
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure is thorough, and will fully convey
the scope of the invention to those skilled in the art. In the
drawings, the size and relative sizes of layers and regions may be
exaggerated for clarity. Like reference numerals in the drawings
denote like elements.
[0023] It will be understood that when an element is referred to as
being "connected to" another element, it can be directly connected
to the other element, or intervening elements may be present. In
contrast, when an element is referred to as being "directly
connected to" another element, there are no intervening elements
present.
[0024] Always_on technology included in the present invention will
now be explained briefly prior to describing the exemplary
embodiments.
[0025] Always_on technology is technology that always maintains a
Point to Point Protocol (PPP) connection of a data link between a
mobile terminal and a PDSN/FA. If the mobile terminal is powered on
and Always_on technology is activated, the PPP configuration
between the mobile terminal and a network is maintained.
Maintaining the PPP configuration equates to maintaining an
authentication process and the network protocol configuration
between end-to-end nodes even without data traffic. Thus, while
maintaining the PPP configuration, data can be directly received
and/or transmitted between the mobile terminal and PDSN/FA without
a separate PPP connection process.
[0026] FIG. 2 is a block diagram of a network of a packet switched
radio telecommunication system according to an exemplary embodiment
of the present invention.
[0027] The present invention adapts the Always_on technology to a
link 208a between a target PDSN 205 and a support PDSN 203 as
illustrated in FIG. 2. That is, authentication or a network
protocol for an MS 201 connected to the support PDSN 203 is
previously configured and then maintained. Thus, when an MS 201 is
handed over from the support PDSN 203 to the target PDSN 205, the
support PDSN 203 can directly transmit information of the MS 201
hand over to the target PDSN 205. In addition, the support PDSN 203
can transmit a down-link frame received from the server 207 to the
target PDSN 205.
[0028] In FIG. 2, the support PDSN 203 has an IP pool 209, and the
target PDSN 205 has an IP pool 210. In general, an IP pool such as
IP pool 210 includes temporary IP addresses that may be assigned to
a roaming MS 201 by a target PDSN/FA 205 via target BSC/PCF 204. A
target PDSN/FA 205 temporarily assigns one of temporary IP
addresses in the IP pool 210 to the MS 201 that configures a
connection to the target PDSN/FA 205. The IP pool is exemplified as
follows:
[0029] IP pool 210 in target PDSN: (3.0.0.1), (3.0.0.2), (3.0.0.3),
(3.0.0.4), . . .
[0030] IP pool 209 in support PDSN: (2.0.0.1), (2.0.0.2),
(2.0.0.3), (2.0.0.4), . . .
[0031] However, according to the present invention, the MS 201 is
assigned with a temporary IP address from the support PDSN 203 and
transmits data to the server 207 via link 201a, 202a, 203a, and
204a. If the MS 201 is handed over to the target PDSN 205, the MS
continues to use the temporary IP address assigned from the support
PDSN 203 without being assigned with a temporary IP address from
the target PDSN 205.
[0032] For example, an inherent IP address of the MS 201 registered
in its HA 208 may be 1.0.0.1, and a temporary IP address assigned
from the support PDSN 203 is 2.0.0.1.
[0033] Data intended for the MS 201 is transmitted from the server
207 to the Internet 206 via a link 204a and then to the HA 208 via
a link 205a. The data is encapsulated at the HA 208. The
encapsulated data is transmitted from the HA 208 to the Internet
206 via link 205a, and then to the current support PDSN 203 via the
link 203a. The encapsulated data transmitted to the support PDSN
203 is transmitted to the MS 201 having the temporary IP address
2.0.0.1 via a support BSC/PCF 202. To transmit data, the MS 201
transmits data to the server 207 via link 201a, link 202a, link
203a, and the link 204a without passing through the HA 208.
[0034] When the MS 201 carries out handover, the support PDSN 203
transmits handover data to the target PDSN 205 via the direct link
208a without transmitting the same to the core network, which
includes the Internet 206 and the server 207. Herein, the support
PDSN 203 transmits the temporary IP address 2.0.0.1 assigned to the
MS 201 to the target PDSN 205.
[0035] Then, the MS 201 carrying out handover requests registration
of the temporary IP address 2.0.0.1 from the target PDSN 205 via
the target BSC/PCF 204. When the temporary IP address included in
the registration request is identical to the temporary IP address
transmitted from the support PDSN 203 to the target PDSN 205 via
the link 208a, the target PDSN 205 temporarily registers the
temporary IP address in its IP pool 210, and allows the MS 201 to
use the temporary IP address continuously.
[0036] In addition, down-link frame data transmitted from the
server 207 to the support PDSN 203 via the HA 208 is transmitted to
the target PDSN 205 via a link 208a, and then the down-link frame
data transmitted to the target PDSN 205 is transmitted to the MS
201 using the temporary IP address 2.0.0.1 via link 207a. The MS
201 being in an activated state and using the temporary IP address
assigned by support PDSN 203 can carry out handover without data
corruption or loss through the above process.
[0037] If the MS 201, which has carried out handover to the target
PDSN 205 and still uses the temporary IP address assigned by the
support PDSN 203, enters into a data dormant state, or has
completed data transmission, the MS 201 may relinquish the
temporary IP address 2.0.0.1 of the support PDSN 203 to the support
PDSN 203. The MS 201 is then assigned with a new temporary IP
address 3.0.0.1 through a new PPP connection to the target PDSN
205, and registers a Care-of Address (CoA) of the target FA 205 in
the core network including the HA 208. Then, when the MS 201 comes
out of the dormant state, or receives/transmits data again, the
server 207 transmits the data to the target PDSN 205 at the CoA via
the HA 208, link 205a, and link 206a, and then the target PDSN 205
transmits the data to the MS 201 assigned with the temporary IP
address 3.0.0.1.
[0038] FIG. 3 is a flow chart illustrating a method for hard
handover in the packet switched radio telecommunication system
according to an exemplary embodiment of the present invention.
[0039] As illustrated in FIG. 3 a direct link is configured between
a support PDSN and a target PDSN using Always_on technology at step
S301. That is, the target PDSN configures the authentication for
the MS having been connected to the support PDSN or configures a
network protocol, and maintains the same.
[0040] Then, if the MS connected to the support PDSN carries out
handover, the support PDSN transmits to the target PDSN 205 the
handover data of the MS and the temporary IP address data assigned
to the MS by the support PDSN at step S302.
[0041] Next, the MS requests the target PDSN for registration of
the currently used temporary IP address assigned by the support
PDSN via the target BSC at step S303.
[0042] The target PDSN compares the temporary IP address in the
registration request from the MS with the temporary IP address
transmitted by the support PDSN via the direct link at step
S304.
[0043] If the temporary IP address in the registration request from
the MS is identical to the temporary IP address transmitted by the
support PDSN, the target PDSN temporarily registers the temporary
IP address in its IP pool at step S305.
[0044] Then, down-link frame data transmitted from the internet
server via the HA to the support PDSN is transmitted to the target
PDSN via the direct link at step S306.
[0045] The target PDSN receives the down-link frame data
transmitted via the direct link and transmits the down-link frame
data to the MS carrying out handover via the target BSC at step
S307.
[0046] Meanwhile, if the MS is in a data dormant state, or has
completed data transmission, the MS gives back the temporary IP
address assigned by the support PDSN to the support PDSN at step
S308.
[0047] Then, the MS is assigned a new temporary IP address for a
new PPP connection by the target PDSN, and registers the CoA of the
changed FA in the core network including the HA at step S309.
[0048] Then, if the MS comes out of the dormant state, or
receives/transmits data again, the internet server transmits the
down-link frame data to the target PDSN at the CoA via the HA at
step S310
[0049] The target PDSN transmits the down-link frame data to the MS
assigned to the new temporary IP address at step S311.
[0050] The above-mentioned method of the present invention may be
embodied into a program so that it is stored in a recording medium,
such as CD-ROM, RAM, floppy disc, hard disc, magneto-optical disc,
in a form readable by a computer.
[0051] As set forth before, according to the present invention, a
direct link is configured between the target PDSN and the support
PDSN, thereby reducing a time delay in requesting handover. The
handover is performed without informing the core network of the
handover state of the MS, thereby reducing a delay occurring due to
the core network. Moreover, in performing the handover by the MS,
the IP re-configuration is not needed so that data corruption or
loss may not occur.
[0052] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the invention. Thus
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *